On the non-axisymmetric fragmentation of rings generated by the secular gravitational instability

Ringed structures have been observed in a variety of protoplanetary discs. Among the processes that might be able to generate such features, Secular Gravitational Instability (SGI) is possible candidate. It has also proposed SGI lead formation planetesimals during non-linear phase instability. In this context, we employ two-fluid hydrodynamical simulations with self-gravity study non-axisymmetric, evolution ringed perturbations grow under action SGI. We find outcome depends mainly on initial linear growth rate. For rates smaller than typically $\sigma \gtrsim 10^{-4}-10^{-5}\Omega$, dissipation resulting from dust feedback introduces $m=1$ spiral wave gas, even for Toomre gas stability parameters $Q_g>2$ which non-axisymmetric instabilities appear purely gaseous disc. This one-armed subsequently traps particles until dust-to-gas ratio $\epsilon \sim 1$ achieved. higher rates, ring found undergo gravitational collapse bump surface density profile becomes strong enough trigger dusty vortices through Rossby Wave (RWI). Enhancements process are scale rate, and can Roche density, leading bound clumps. Fragmentation axisymmetric rings produced by therefore as planetesimals.